U.S. patent application number 15/021727 was filed with the patent office on 2016-08-11 for suspension arm member.
The applicant listed for this patent is NHK SPRING CO., LTD.. Invention is credited to Shigeru KURODA.
Application Number | 20160229247 15/021727 |
Document ID | / |
Family ID | 52778352 |
Filed Date | 2016-08-11 |
United States Patent
Application |
20160229247 |
Kind Code |
A1 |
KURODA; Shigeru |
August 11, 2016 |
SUSPENSION ARM MEMBER
Abstract
A suspension arm member includes a connecting portion configured
to connect plural members of a suspension, and a support bar
extending and provided with the connecting portion at each end. The
support bar is made of a resin material and includes plural
lightening hole portions each formed in a shape of a recessed
portion. The lightening hole portions include plural front upper
lightening hole portions (11) formed in a front upper portion of
the support bar, plural front lower lightening hole portions formed
in a front lower portion of the support bar, plural rear upper
lightening hole portions formed in a rear upper portion of the
support bar, and plural rear lower lightening hole portions formed
in a rear lower portion of the support bar.
Inventors: |
KURODA; Shigeru;
(Yokohama-city, Kanagawa, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NHK SPRING CO., LTD. |
Yokohama-city, Kanagawa |
|
JP |
|
|
Family ID: |
52778352 |
Appl. No.: |
15/021727 |
Filed: |
October 2, 2013 |
PCT Filed: |
October 2, 2013 |
PCT NO: |
PCT/JP2013/076840 |
371 Date: |
March 14, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B60G 2206/11 20130101;
B60G 2206/7101 20130101; B60G 2204/416 20130101; B60G 2204/1224
20130101; B60G 2206/10 20130101; B60G 7/005 20130101; B60G 7/001
20130101 |
International
Class: |
B60G 7/00 20060101
B60G007/00 |
Claims
1. A suspension arm member comprising: a connecting portion
configured to connect a plurality of members of a suspension
mounted on a vehicle; and a support bar provided with the
connecting portion at each end and extending in a longitudinal
direction, wherein the support bar is made of a resin material and
comprises a plurality of lightening hole portions each formed in a
shape of a recessed portion in a direction orthogonal to the
longitudinal direction, wherein the lightening hole portions
comprise a plurality of front upper lightening hole portions formed
in the longitudinal direction in a front upper portion of the
support bar, a plurality of front lower lightening hole portions
formed in the longitudinal direction in a front lower portion of
the support bar and staggered in a top-to-bottom direction with
respect to the front upper lightening hole portions, a plurality of
rear upper lightening hole portions formed in the longitudinal
direction in a rear upper portion of the support bar and staggered
in a front-to-rear direction with respect to the front upper
lightening hole portions, and a plurality of rear lower lightening
hole portions formed in the longitudinal direction in a rear lower
portion of the support bar and staggered with respect to the rear
upper lightening hole portions and the front lower lightening hole
portions.
2. The suspension arm member according to claim 1, wherein parts of
the support bar in which the lightening hole portions are formed
are formed in substantially an S-shape or in substantially an
inverted S-shape, as seen in a cross-sectional view in a widthwise
direction.
3. The suspension arm member according to claim 1, wherein the
parts in which the lightening hole portions are formed comprise an
intermediate plate portion disposed in a central portion as seen in
the cross-sectional view in the widthwise direction, rib portions
formed so as to extend in opposite directions from ends of the
intermediate plate portion in a direction orthogonal to the
intermediate plate portion, and wing portions formed so as to
extend from distal ends of the rib portions and parallel to a
direction orthogonal to the rib portions, wherein the lightening
hole portions are formed so that the following equation is
satisfied: T1<T3<T2 where T1 represents a plate thickness of
the intermediate plate portion, T2 represents a plate thickness of
the rib portion, and T3 represents a plate thickness of the wing
portion.
4. The suspension arm member according to claim 1, wherein the
lightening hole portions are provided with sidewalls, and the
sidewalls are formed so as to extend from openings to inner bottom
portions of the lightening hole portions and so as to have an angle
of inclination such that the sidewalls are expanded to the
openings.
5. The suspension arm member according to claim 4, wherein the
sidewalls are formed so that the sidewalls are expanded in an
opposite direction to the adjacent respective lightening hole
portions.
6. The suspension arm member according to claim 4, wherein the
angle of inclination comprises any angle in a range of 91 to 100
degrees with respect to a centerline of the support bar in the
longitudinal direction.
7. The suspension arm member according to claim 1, wherein corner
portions of the lightening hole portions are rounded with their
respective predetermined radii of curvature.
8. The suspension arm member according to claim 1, wherein the
resin material comprises engineering plastic or super engineering
plastic containing any of PA (polyamide) 66, PA 6, PPS
(polyphenylene sulfide), and POM (polyoxymethylene).
9. The suspension arm member according to claim 8, wherein the
resin material comprises a fiber reinforcement material added
thereto.
Description
TECHNICAL FIELD
[0001] The present invention relates to a suspension arm member
which is utilized for connecting plural members in a suspension
mounted on a vehicle.
BACKGROUND ART
[0002] Heretofore, in a suspension mounted on an automobile, one
member has been connected to another member in a vertically or
otherwise swingable manner with a suspension arm member interposed
in between. Examples of the suspension arm member include a
suspension arm mounted to a vehicle body or an axle by a ball
joint, and a stabilizer link connecting a strut and a stabilizer.
Such a suspension arm member is required to have strength or
rigidity, and thus, a suspension arm member made of iron is
generally used. A typical stabilizer link is heavier in weight due
to its support bar made of steel, as compared to a member made of a
resin or a member made of aluminum.
[0003] Recently, in the field of automobiles, there has been a
growing demand for an improvement in fuel economy because of a
steep rise in crude oil and gasoline prices or the like, and there
has been a demand for a weight reduction of the vehicle body for
purposes of the improvement in the fuel economy. A plastic pendulum
support disclosed in Patent Literature 1, for example, is known as
the suspension arm member whose weight is reduced in order to
reduce the weight of the vehicle body.
[0004] The plastic pendulum support (or the suspension arm member)
disclosed in Patent Literature 1 has eight intermediate chambers in
total by forming four longitudinally-elongate intermediate chambers
in front and rear lateral sides, respectively, of a base body made
of plastic.
[0005] The intermediate chambers include a pair of front lateral
central intermediate chambers disposed in a central lower side of
the front lateral side of the plastic pendulum support, a pair of
front lateral outside intermediate chambers disposed at left and
right outside upper symmetrical positions, respectively, with
respect to the pair of front lateral central intermediate chambers,
a pair of rear lateral upper central intermediate chambers disposed
in a central upper side of the rear lateral side, and a pair of
rear lateral outside upper intermediate chambers disposed at left
and right outside lower symmetrical positions, respectively, with
respect to the pair of rear lateral upper central intermediate
chambers.
[0006] In the plastic pendulum support, the four
longitudinally-elongate intermediate chambers are formed in the
front and rear lateral sides, respectively, in an S-shape as seen
in a vertical sectional view in a widthwise direction, thereby
improving cross-sectional secondary moment and load resistance
capability of the entire construction.
CITATION LIST
Patent Literature
[0007] Patent Literature 1: JP 2009-541680 A
SUMMARY OF INVENTION
Technical Problem
[0008] However, there is a demand for further reductions in weight
and manufacturing cost, although in the plastic pendulum support
disclosed in Patent Literature 1, the four intermediate chambers
(or intermediate spaces) are formed in the front lateral side and
the rear lateral side, respectively, and are manufactured from
plastic thereby to achieve a weight reduction and a manufacturing
cost reduction.
[0009] Moreover, in the plastic pendulum support, the base body is
not formed in a vertically symmetrical shape about a centerline, as
seen in a side view, and thus, if an automobile travels with the
plastic pendulum support mounted thereon, the plastic pendulum
support is subjected to loads from multiple directions and hence
undergoes irregular deformation without becoming deformed in a
vertically symmetrical shape. For example, if the plastic pendulum
support is used as the stabilizer link in the automobile, the
plastic pendulum support rotates in a forward or reverse direction
about a longitudinally extending axis, which thus requires a space
for a circumscribed circle around the plastic pendulum support.
Thus, if auxiliary machinery or the like is disposed around the
stabilizer link, the plastic pendulum support abuts against the
auxiliary machinery or the like, which in turn requires a space for
avoiding such abutting and hence leads to the problem of making it
difficult to design a vehicle layout.
[0010] Moreover, in the plastic pendulum support, the intermediate
chambers formed in the support bars between receiving elements on
both ends are formed in square-shaped spaces by three upper, middle
and lower transverse webs (or ribs) and two coupling portions. This
leads to the problem of making it difficult to remove mud and sand
or the like if the mud and sand or the like is deposited on the
intermediate chambers at their backs and corners.
[0011] Moreover, in the plastic pendulum support, the three upper,
middle and lower transverse webs in the form of flat plates are
arranged parallel to one another, and thus, the plastic pendulum
support has the problem of being weak against the behavior of axial
displacement of the upper and lower transverse webs, although being
strong against a compression force from a direction orthogonal to
the axis.
[0012] Moreover, the plastic pendulum support has the problem that
stresses are prone to concentrate at the points of intersection of
the transversely-formed transverse webs and vertically-formed
coupling webs and hence acute-angled corners are prone to
break.
[0013] Therefore, the present invention has been made in order to
overcome the foregoing problems. An object of the present invention
is to provide a suspension arm member which is lighter in weight
and higher in strength.
Solution to Problem
[0014] To solve the above problems, the present invention provides
a suspension arm member including: a connecting portion configured
to connect plural members of a suspension mounted on a vehicle; and
a support bar provided with the connecting portion at each end and
extending in a longitudinal direction, wherein the support bar is
made of a resin material and includes plural lightening hole
portions each formed in a shape of a recessed portion in a
direction orthogonal to the longitudinal direction, and the
lightening hole portions include plural front upper lightening hole
portions formed in the longitudinal direction in a front upper
portion of the support bar, plural front lower lightening hole
portions formed in the longitudinal direction in a front lower
portion of the support bar and staggered in a top-to-bottom
direction with respect to the front upper lightening hole portions,
plural rear upper lightening hole portions formed in the
longitudinal direction in a rear upper portion of the support bar
and staggered in a front-to-rear direction with respect to the
front upper lightening hole portions, and plural rear lower
lightening hole portions formed in the longitudinal direction in a
rear lower portion of the support bar and staggered with respect to
the rear upper lightening hole portions and the front lower
lightening hole portions.
[0015] Note that the terms "top-to-bottom direction," "upper" and
"lower" as employed herein refer to arbitrary directions, and a
widthwise direction with respect to a surface in which the
lightening hole portions are formed is defined as the top-to-bottom
direction. Also, the terms "front-to-rear direction," "front" and
"rear" refer to arbitrary directions, and a depth direction in
which the lightening hole portions each in the shape of the
recessed portion are formed is defined as the front-to-rear
direction.
[0016] According to such a configuration, the suspension arm member
includes the plural lightening hole portions each formed in the
shape of the recessed portion and is made of the resin material,
thus enabling a weight reduction. The lightening hole portions
include the front upper lightening hole portions formed in the
front upper portion of the support bar, the front lower lightening
hole portions formed in the front lower portion of the support bar
and staggered in the top-to-bottom direction with respect to the
front upper lightening hole portions, the rear upper lightening
hole portions formed in the rear upper portion of the support bar
and staggered with respect to the front upper lightening hole
portions, and the rear lower lightening hole portions formed in the
rear lower portion of the support bar and staggered with respect to
the rear upper lightening hole portions and the front lower
lightening hole portions. Thus, the suspension arm member includes
the arrangement of the lightening hole portions formed in the front
and the rear of the support bar and staggered in the top-to-bottom
direction and in the longitudinal direction, which in turn enables
reducing the resin material for the support bar by the amount of
lightening and hence achieving a cost reduction and a weight
reduction and also enables an improvement in strength by a
partition part in which the lightening hole portions are
formed.
[0017] Preferably, moreover, parts of the support bar in which the
lightening hole portions are formed are formed in substantially an
S-shape or in substantially an inverted S-shape, as seen in a
cross-sectional view in a widthwise direction.
[0018] According to such a configuration, in the support bar, the
parts in which the lightening hole portions are formed are formed
in substantially the S-shape or in substantially the inverted
S-shape, as seen in the cross-sectional view in the widthwise
direction, which thus enables an improvement in rigidity of the
lightening hole portions.
[0019] Preferably, moreover, the parts in which the lightening hole
portions are formed include an intermediate plate portion disposed
in a central portion as seen in the cross-sectional view in the
widthwise direction, rib portions formed so as to extend in
opposite directions from ends of the intermediate plate portion in
a direction orthogonal to the intermediate plate portion, and wing
portions formed so as to extend from distal ends of the rib
portions and parallel to a direction orthogonal to the rib
portions, and the lightening hole portions are formed so that the
following equation is satisfied: T1<T3<T2, where T1
represents a plate thickness of the intermediate plate portion, T2
represents a plate thickness of the rib portion, and T3 represents
a plate thickness of the wing portion.
[0020] According to such a configuration, the lightening hole
portions are formed so that the plate thickness T1 of the
intermediate plate portion, the plate thickness T2 of the rib
portion and the plate thickness T3 of the wing portion satisfy the
following equation: T1<T3<T2, and thus, during resin molding,
resin fluidity can be applied to requirements for higher strength.
Thus, the support bar having rigidity can be achieved.
[0021] Preferably, moreover, the lightening hole portions are
provided with sidewalls, and the sidewalls are formed so as to
extend from openings to inner bottom portions of the lightening
hole portions and so as to have an angle of inclination such that
the sidewalls are expanded to the openings.
[0022] According to such a configuration, in the lightening hole
portions, the sidewalls formed extending from the openings to the
inner bottom portions are formed so as to have the angle of
inclination such that the sidewalls are expanded to the openings in
a fan shape as seen in the cross-sectional view, which thus enables
easy removal of a mold after the resin molding and also enables
easy elimination of mud and sand or the like which has entered into
the lightening hole portions.
[0023] Preferably, moreover, the sidewalls are formed so that the
sidewalls are expanded in an opposite direction to the adjacent
respective lightening hole portions.
[0024] According to such a configuration, the sidewalls of the
lightening hole portions are expanded in the opposite direction to
the adjacent respective lightening hole portions, which thus
enables the resin molding so as to suppress the falling down of the
wing portions at an open end side by a truss effect and also
enables ensuring uniform strength in an axial direction.
[0025] Preferably, moreover, the angle of inclination includes any
angle in a range of 91 to 100 degrees with respect to a centerline
of the support bar in the longitudinal direction.
[0026] According to such a configuration, the angle of inclination
of the sidewalls of the lightening hole portions is any angle in
the range of 91 to 100 degrees, which thus enables easy removal of
the mold after the resin molding and also enables easy elimination
of mud and sand or the like which has entered into the lightening
hole portions during the travel of the vehicle. Moreover, the
sidewalls of the lightening hole portions are inclined so as to be
expanded, which thus enables an improvement in strength of the
support bar.
[0027] Preferably, moreover, corner portions of the lightening hole
portions are rounded with their respective predetermined radii of
curvature.
[0028] According to such a configuration, the corner portions of
the lightening hole portions are rounded with their respective
predetermined radii of curvature, which thus enables suppressing a
situation where stresses concentrate at the corner portions and
hence break the corner portions when other members collide against
the corner portions.
[0029] Preferably, moreover, the resin material includes
engineering plastic or super engineering plastic containing any of
PA (polyamide) 66, PA 6, PPS (polyphenylene sulfide), and POM
(polyoxymethylene).
[0030] According to such a configuration, the resin material is
made of the engineering plastic or the super engineering plastic,
which thus enables improvements in strength and heat
resistance.
[0031] Preferably, moreover, the resin material includes a fiber
reinforcement material added thereto.
[0032] According to such a configuration, the resin material
includes the fiber reinforcement material added thereto, which thus
enables improvements in rigidity and strength against
temperature.
Advantageous Effects of Invention
[0033] According to the present invention, a suspension arm member
which is lighter in weight and higher in strength can be
provided.
BRIEF DESCRIPTION OF DRAWINGS
[0034] FIG. 1 is a front view with a partial cross section of a
suspension arm member according to an embodiment of the present
invention;
[0035] FIG. 2A is an enlarged cross-sectional view taken along the
line A-A of FIG. 1;
[0036] FIG. 2B is an enlarged bottom view of a connecting portion
of the suspension arm member;
[0037] FIG. 3A is a side view of a support bar of the suspension
arm member;
[0038] FIG. 3B is a cross-sectional view taken along the line B-B
of FIG. 3A;
[0039] FIG. 4A is a cross-sectional view taken along the line C-C
of FIG. 3A;
[0040] FIG. 4B is a cross-sectional view taken along the line D-D
of FIG. 3B;
[0041] FIG. 5A is a cross-sectional view taken along the line E-E
of FIG. 3A;
[0042] FIG. 5B is a cross-sectional view taken along the line F-F
of FIG. 3A;
[0043] FIG. 5C is a cross-sectional view taken along the line G-G
of FIG. 3A;
[0044] FIG. 5D is a cross-sectional view taken along the line F-F
of FIG. 3A; and
[0045] FIG. 6 is an enlarged cross-sectional view of a principal
part, showing a shape of a lightening hole portion.
DESCRIPTION OF EMBODIMENTS
[0046] Hereinafter, a suspension arm member S according to an
embodiment of the present invention will be described with
reference to FIGS. 1 to 6.
[0047] Note that the suspension arm member S shown in FIG. 1
changes its orientation according to its installed state in a
vehicle or its mounted position. Thus, for the sake of convenience,
description will be given below, provided that with reference to a
case where a support bar 1 is disposed in a longitudinal direction
in the suspension arm member S, a depth direction of lightening
hole portions 10 formed in the support bar 1 is defined as a
front-to-rear direction, a widthwise direction of the lightening
hole portions 10 of the support bar 1 is defined as a top-to-bottom
direction, and the sides on which connecting portions 2, 2 are
disposed are defined as left and right.
[0048] (Configuration of Suspension)
[0049] Prior to description of the suspension arm member S
according to the embodiment of the present invention, description
will first be given with regard to a suspension (not shown) to
which the present invention is applied.
[0050] The suspension (not shown) is a device configured to mount a
vehicle body thereon in a vehicle such for example as an
automobile, a motorcycle or an electric train and absorb vibrations
from wheels, and includes the suspension arm member S.
[0051] (Configuration of Suspension Arm Member)
[0052] The suspension arm member S is an arm-shaped member provided
in the suspension (not shown) mounted on the vehicle, and also
includes a member called a link or a rod. The suspension arm member
S is, for example, a suspension arm or a stabilizer link or the
like. Any member may be adopted as the suspension arm member S as
long as it has the support bar 1 to be described later and is used
in the suspension (not shown), and the form, type and used location
of the suspension or the like is not particularly limited.
Hereinafter, the present invention will be described giving the
case of the stabilizer link by way of example.
[0053] As shown in FIG. 1, the suspension arm member S is the
arm-shaped (or link-shaped) member including a pair of connecting
portions 2, 2 configured to connect plural members of the
suspension mounted on the vehicle, and the support bar 1 provided
with the connecting portions 2, 2 at its ends, respectively, and
extending in the longitudinal direction. In the suspension arm
member S, a ball seat 3 to be described later, a stud bolt 4 having
a ball portion 4a rotatably provided within the ball seat 3, and a
dust boot 5 for preventing dust or the like from entering the ball
portion 4a are disposed in a housing portion 2a of the connecting
portions 2, 2 at the ends.
[0054] For example, the suspension arm member S is formed so that
its overall length L1 (see FIG. 4B) is of the order of 330 mm. The
suspension arm member S is made of a resin material including
so-called engineering plastic or super engineering plastic
containing any of PA (polyamide) 66, PA 6, PPS (polyphenylene
sulfide), and POM (polyoxymethylene). The resin material includes a
fiber reinforcement material added thereto, and the fiber
reinforcement material includes fine fibers such as glass fibers or
carbon fibers, or the like, which thus improves strength.
Preferably, the percentage of content of the fiber reinforcement
material in the resin material is equal to or higher than 25% in
order to prevent a reinforcement effect and a high-temperature
(80.degree. C.) strength from being equal to or less than 50%, as
compared to normal temperature (23.degree. C.). Moreover, an upper
limit of the percentage of content of the fiber reinforcement
material is set to about 60%, taking into account life of an
injection molding machine as a matter of moldability.
[0055] As employed herein, the "engineering plastic" refers to
high-performance plastic adaptable to structural and mechanical
members, having a heat resistance of 100.degree. C. or higher, a
tensile strength of 50 MPa or higher, and a modulus of flexural
elasticity of 2.4 GPa or higher. Also, the "super engineering
plastic" refers to engineering plastic having higher heat
resistance, which can be used over a long term even at a high
temperature of 150.degree. C. or more.
[0056] PA 66 is a polyamide-base resin and is also called nylon 66.
PA 66 is a synthetic fiber and is also engineering plastic having
higher crystallinity among the polyamide-base resins and having
well-balanced physical properties, and PA 66 is superior in heat
resistance and mechanical strength, as compared to PA 6. PA 66 is
superior in balance of mechanical strength and chemical resistance,
and has most excellent mechanical strength among nylon-base resins
(or the polyamide-base resins). Moreover, PA 66 can be reinforced
by a filler, and PA 66 can be filled with glass fibers or the like
to greatly improve mechanical strength, rigidity, heat distortion
temperature, or the like.
[0057] PA 6 is a polyamide resin and is also called nylon 6. PA 6
has a melting point of 225.degree. C., a heat resistance
temperature of 80 to 140.degree. C., a specific gravity of 1.13 and
a translucent white color, and is superior in wear resistance, cold
proof resistance, shock resistance, oil resistance and alkali
resistance.
[0058] PPS is a polyphenylene sulfide resin and is a
high-performance resin having a molecular structure including a
phenyl group (or a benzene cycle) and sulfur (S) repeatedly
alternating with each other. PPS is a crystalline resin and is very
high in heat resistance (or has a continuous enduring temperature
of the order of 240.degree. C.), and PPS is superior in heat
resistance because of having a continuous enduring temperature of
200.degree. C. to 220.degree. C. and a load deflection temperature
of 260.degree. C. or higher under high load (1.82 MPa) and is high
in tensile strength and flexural strength. PPS has a low shrinkage
percentage of 0.3 to 0.5% during molding and has good dimensional
stability. Moreover, PPS is superior in mechanical strength,
rigidity, inflammability, chemical resistance, electrical
properties, dimensional stability, and the like.
[0059] POM is polyacetal and is a crystalline resin having
well-balanced mechanical properties and is extremely superior in
fatigue resistance, in particular. POM is superior in friction
resistance, wear resistance, chemical resistance, creep resistance
and dimensional stability and is also low in water
absorbability.
(Configuration of Support Bar)
[0060] As shown in FIGS. 4A and 4B, the support bar 1 is a
rod-shaped part disposed between the connecting portions 2, 2 at
the left and right ends, and is integrally formed with the
connecting portions 2, 2 by the resin material. The support bar 1
includes the plural lightening hole portions 10 each formed in a
shape of a recessed portion in a direction (or the front-to-rear
direction) orthogonal to the longitudinal direction (or a
left-to-right direction) and disposed in two upper and lower
stages, and end lightening hole portions 15 formed in a row
extending from the left and right sides of the lightening hole
portions 10 to the connecting portions 2, 2 at the left and right
ends, as seen in a front view.
[0061] For example, the support bar 1, as seen in a plan view, is
formed so that a length L2 of a central portion in the
front-to-rear direction is of the order of 26.2 mm and a length L3
of the end portion (or a neck portion le) close to the connecting
portion 2 in the front-to-rear direction is 20.83 mm. In other
words, the support bar 1 is formed longest in the central portion
and narrowest in the end portion, so that its length gradually
decreases from the central portion toward the end portions. For
example, the support bar 1, as seen in a side view, is formed so
that a height H1 of the central portion in the top-to-bottom
direction is of the order of 19.6 mm and a height H2 of the left
and right ends in the top-to-bottom direction is 15.40 mm. In other
words, the support bar 1 is formed longest in the central portion
and narrowest in the end portions, so that the support bar 1
becomes gradually narrower from the central portion toward the
ends. Moreover, as shown in FIGS. 5A to 5C, in the support bar 1,
all corner portions 10d at which plane surfaces such as the
lightening hole portions 10 intersect one another are provided with
curves Ra, Rb to be described later or a spherical curved surface
Rc, and are rounded with their respective predetermined radii of
curvature.
[0062] As shown in FIGS. 5B and 5C, parts of the support bar 1 in
which the lightening hole portions 10 are formed are formed in
substantially an S-shape or in substantially an inverted S-shape,
as seen in a vertical sectional view. The parts of the support bar
1 in which the lightening hole portions are formed include an
intermediate plate portion 10e, rib portions 10f, and wing portions
10g, to be described later. The support bar 1 is formed in
substantially the S-shape or in substantially the inverted S-shape
as seen in the vertical sectional view, and thus, the rib portions
10f and the wing portions 10g are disposed at positions at a
distance away from a central axis in an X-axis direction and a
Y-axis direction, as compared to a support bar having an I-shape as
seen in the vertical sectional view. Thus, the support bar 1, if
loaded by an external force, can distribute and elastically absorb
the external force, which in turn enables suppressing an external
dimension and hence achieving a size reduction.
[0063] (Configuration of Lightening Hole Portion)
[0064] As shown in FIG. 1, the lightening hole portions 10 are
spaces each in a shape of a recessed portion as seen in a
cross-sectional view, formed in the front and the rear of the
support bar 1 and in outer peripheral surfaces of the connecting
portions 2, 2, and the lightening hole portions 10 are formed for
purposes of a weight reduction of the suspension arm member S. The
lightening hole portions 10 include front upper lightening hole
portions 11, front lower lightening hole portions 12, rear upper
lightening hole portions 13, rear lower lightening hole portions
14, and the end lightening hole portions 15.
[0065] As shown in FIG. 3B, the lightening hole portions 10 are
provided with sidewalls 10c, and the sidewalls 10c are formed so as
to extend from openings 10a to inner bottom portions 10b of the
lightening hole portions 10 and so as to have an angle .theta. of
inclination such that the sidewalls 10c are expanded to the
openings 10a in a fan shape as seen in the cross-sectional view.
The angle .theta. of inclination is formed as any angle in a range
of 91 to 100 degrees with respect to a centerline of the support
bar 1 in the left-to-right (or longitudinal) direction. Thus, the
lightening hole portions 10 are formed so as to expand so that
their bore diameters become gradually larger from the inner bottom
portions 10b toward the openings 10a.
[0066] In FIGS. 1, 3B and 4B, for the sake of convenience, the
openings 10a and the sidewalls 10c are represented as straight
lines and are omitted; however, actually, there is an offset (or a
step) between an open end and a bottom end of the opening 10a.
[0067] (Configuration of Front Upper Lightening Hole Portion)
[0068] As shown in FIG. 3A, the front upper lightening hole
portions 11 include the four lightening hole portions 10 formed in
a row in the longitudinal direction in a front upper portion 1a of
the support bar 1, at spaced intervals for disposition such that
the rear upper lightening hole portions 13 (see FIG. 1) can be
formed. The front upper lightening hole portions 11 include a pair
of first front upper lightening hole portions 11a and a pair of
second front upper lightening hole portions 11b, and these pairs
are symmetrically disposed in the left-to-right direction. The pair
of first front upper lightening hole portions 11a are disposed at
left and right positions close to the central portion with respect
to the central portion in the left-to-right (or longitudinal)
direction, and the pair of second front upper lightening hole
portions 11b are disposed at positions close to the connecting
portions 2, 2 of the pair of first front upper lightening hole
portions 11a. Lengths L11 of the four front upper lightening hole
portions 11 in the left-to-right direction are all the same and are
20 mm, for example.
[0069] The front upper lightening hole portions 11 are formed so
that heights H11a, H11b of the four front upper lightening hole
portions 11 in the top-to-bottom direction decrease proportionally
according to a gradual decrease in a height dimension of the
support bar 1 from the height H1 of the central portion in the
top-to-bottom direction toward the height H2 of the end portions.
Each front upper lightening hole portion 11 is formed so that the
height H11a close to the central portion of the support bar 1 is
greater than the height H11b close to the connecting portions 2, 2,
and thus, each front upper lightening hole portion 11 is formed in
a trapezoidal shape which is long in a transverse direction. In
other words, each front upper lightening hole portion 11 is formed
so as to be inclined so that the upper wing portion 10g becomes
lower with respect to the horizontally-extending intermediate plate
portion 10e from the central portion of the support bar 1 toward
the connecting portions 2, 2.
[0070] The four front upper lightening hole portions 11 formed in
this manner include the symmetrical formation and disposition of
the two front upper lightening hole portions 11 disposed on the
left side and the two front upper lightening hole portions 11
disposed on the right side, with respect to the central portion of
the support bar 1 in the longitudinal direction.
[0071] As shown in FIG. 3B, the front upper lightening hole
portions 11 are formed so that in the support bar 1, the length L2
of the central portion in the front-to-rear direction is the
longest length and the length L3 of the neck portion le in the
front-to-rear direction is the shortest length. Thus, a depth D11
of the front upper lightening hole portions 11 disposed at the
positions close to the central portion is formed greater than the
depth D11 of the front upper lightening hole portions 11 disposed
close to the neck portion 1e.
[0072] (Configuration of Front Lower Lightening Hole Portion)
[0073] As shown in FIGS. 3A and 3B, the front lower lightening hole
portions 12 include the five lightening hole portions 10 formed in
the longitudinal direction in a front lower portion lb of the
support bar 1 and staggered in the top-to-bottom direction with
respect to the front upper lightening hole portions 11. The front
lower lightening hole portions 12 are formed in a row from the
central portion of the support bar 1 in the longitudinal direction,
at spaced intervals for disposition such that the rear lower
lightening hole portions 14 (see FIG. 4A) can be formed. The front
lower lightening hole portions 12 include a first front lower
lightening hole portion 12a disposed in the central portion in the
longitudinal direction, a pair of second front lower lightening
hole portions 12b disposed at positions close to the connecting
portions 2, 2 on the left and right of the first front lower
lightening hole portion 12a, and a pair of third front lower
lightening hole portions 12c disposed at positions close to the
connecting portions 2, 2 on the left and right of the second front
lower lightening hole portions 12b, and these portions 12a, 12b and
12c are symmetrically disposed in the left-to-right direction with
respect to the central portion in the longitudinal direction. The
five front lower lightening hole portions 12 are formed so that
lengths, in the left-to-right direction, of the first front lower
lightening hole portion 12a and the second front lower lightening
hole portions 12b disposed at positions close to the central
portion are the same as the length L11 of the front upper
lightening hole portions 11, and the third front lower lightening
hole portions 12c disposed closest to the connecting portions 2, 2
have a length L12 (for example, 30 mm) which is greater than the
length L11.
[0074] In the same manner as the front upper lightening hole
portions 11, the front lower lightening hole portions 12 are formed
so that heights H12a, H12b of the five front lower lightening hole
portions 12 in the top-to-bottom direction decrease proportionally
according to the gradual decrease in the height dimension of the
support bar 1 from the height H1 of the central portion in the
top-to-bottom direction toward the height H2 of the end portions.
The first front lower lightening hole portion 12a in the central
portion is formed in a rectangular shape. In the front lower
lightening hole portions 12, the second front lower lightening hole
portions 12b and the third front lower lightening hole portions 12c
other than the first front lower lightening hole portion 12a are
formed in the same manner as the front upper lightening hole
portions 11, so that the height H12a close to the central portion
of the support bar 1 is greater than the height H12b close to the
connecting portions 2, 2, and thus, the portions 12b and 12c are
formed in a trapezoidal shape which is long in the transverse
direction. In other words, the second front lower lightening hole
portions 12b and the third front lower lightening hole portions 12c
are formed so as to be inclined so that the lower wing portion 10g
becomes lower with respect to the horizontally-extending
intermediate plate portion 10e from the central portion of the
support bar 1 toward the connecting portions 2, 2. Thus, the pair
of left and right second front lower lightening hole portions 12b
and the pair of left and right third front lower lightening hole
portions 12c are symmetrically disposed in a symmetrical shape in
the left-to-right direction with respect to the first front lower
lightening hole portion 12a.
[0075] As shown in FIGS. 4A and 4B, in the front lower lightening
hole portions 12, first rear lower lightening hole portions 14a,
the second front lower lightening hole portions 12b, second rear
lower lightening hole portions 14b, and the third front lower
lightening hole portions 12c are formed in this order from the
first front lower lightening hole portion 12a toward the neck
portions le on the left and right with respect to the first front
lower lightening hole portion 12a disposed in the central portion
of the support bar 1 as seen in a transverse cross-sectional view.
Thus, the front lower lightening hole portions 12, as seen in the
transverse cross-sectional view, are continuously formed in a
concave-convex shape so as to become smaller in size from the
central portion toward the neck portions 1e, in such a manner that
the first front lower lightening hole portion 12a having the
longest length L2 in the front-to-rear direction is disposed in the
central portion and the third front lower lightening hole portions
12c having the shortest length L3 in the front-to-rear direction
are disposed close to the left and right neck portions 1e.
[0076] (Configuration of Rear Upper Lightening Hole Portion)
[0077] As shown in FIG. 3B, the rear upper lightening hole portions
13 include the plural lightening hole portions 10 formed in the
longitudinal direction in a rear upper portion 1c of the support
bar 1 and continuously staggered in the front-to-rear direction
with respect to the front upper lightening hole portions 11. As
shown in FIG. 4B, the rear upper lightening hole portions 13 (13a
to 13c), as seen in the transverse cross-sectional view, are formed
symmetrical to the above-described front lower lightening hole
portions 12 (see FIG. 4A) disposed in the front lower side. Thus,
detailed description will be omitted.
[0078] (Configuration of Rear Lower Lightening Hole Portion)
[0079] As shown in FIG. 4A, the rear lower lightening hole portions
14 include the plural lightening hole portions 10 formed in the
longitudinal direction in a rear lower portion ld of the support
bar 1 and staggered with respect to the rear upper lightening hole
portions 13 (see FIG. 4B) and the front lower lightening hole
portions 12. The rear lower lightening hole portions 14 (14a, 14b),
as seen in the transverse cross-sectional view, are formed
symmetrical to the above-described front upper lightening hole
portions 11 (see FIG. 3B) disposed in the front upper side. Thus,
detailed description will be omitted.
[0080] (Configuration of Sidewall)
[0081] As shown in FIG. 1, the sidewalls 10c are partition walls
formed on left and right inner side surfaces of the lightening hole
portions 10 as seen from the front-to-rear direction, and are
formed in the top-to-bottom direction. As shown in FIG. 3B, the
sidewalls 10c are formed so that the sidewalls 10c are expanded in
an opposite direction to the adjacent respective lightening hole
portions 10 (see FIG. 4A). A plate thickness of the sidewall 10c is
formed so that the thickness is of the order of 2 mm in the same
manner as a plate thickness T2 of the rib portion 10f to be
described later.
[0082] (Configuration of Corner Portion)
[0083] As shown in FIGS. 5A to 5C, in the support bar 1, the corner
portions 10d are always provided with the curves Ra, Rb or the
spherical curved surface Rc. In the support bar 1, the curves Ra,
Rb or the spherical curved surface Rc (see FIG. 6) is formed in the
corner portions 10d thereby to prevent stresses from locally
concentrating when the corner portions 10d are loaded by external
forces.
[0084] As shown in FIGS. 5A to 5C, the curves Ra having R
approximately equal to 0.5, for example, are formed in the corner
portions 10d on outer sides of the lightening hole portions 10.
[0085] The curves Rb are formed in the corner portions 10d which
form sides of the wing portions 10g of the lightening hole portions
10 and sides of the rib portions 10f (or the inner bottom portions
10b). For example, the curve Rb is greater than the curve Ra and
has a radius of curvature in which R=1 mm or R>1 mm (preferably,
R=1 mm to 3 mm).
[0086] Moreover, as shown in FIG. 6, the spherical curved surfaces
Rc are formed in the corner portions 10d at which the rib portions
10f (or the inner bottom portions 10b), the sidewalls 10c and the
intermediate plate portion 10e of the lightening hole portions 10
intersect one another, and in the corner portions 10d at which the
rib portions 10f (or the inner bottom portions 10b), the rib
portions 10f and the wing portions 10g intersect one another. The
spherical curved surface Rc has a radius of curvature in which R32
1 mm or R>1 mm (preferably, R=1 mm to 3 mm).
[0087] (Configuration of Intermediate Plate Portion)
[0088] As shown in FIG. 2A, the intermediate plate portion 10e is a
part in the form of a thick plate, horizontally disposed in the
central portion, in the top-to-bottom direction, of the support bar
1 formed in substantially the S-shape or in substantially the
inverted S-shape as seen in the cross-sectional view in the
widthwise direction. The intermediate plate portion 10e is disposed
in the central portion of the support bar 1 as seen in the vertical
sectional view, and thus, the intermediate plate portion 10e is
disposed at a position where it, when loaded by an external force,
is not loaded by large moment, which in turn enables reducing a
thickness. Thus, the intermediate plate portion 10e is formed with
a plate thickness T1 of 2 mm or more and is formed thinner than the
wing portion 10g. More specifically, the intermediate plate portion
10e is formed with a plate thickness T1 of the order of 2.1 mm, for
example.
[0089] (Configuration of Rib Portion)
[0090] As shown in FIGS. 5A to 5C, the rib portions 10f are parts
each in the form of a thick plate, formed so as to extend in
opposite directions (or in an upward direction or a downward
direction) from ends of the intermediate plate portion 10e in a
direction orthogonal to the intermediate plate portion 10e, and the
rib portions 10f are formed between the intermediate plate portion
10e and the wing portions 10g. The rib portion 10f is thinner than
the intermediate plate portion 10e and is formed with a plate
thickness T2 of the order of 2.0 mm, for example.
[0091] (Configuration of Wing Portion)
[0092] As shown in FIGS. 5A to 5C, the wing portions 10g are parts
each in the form of a thick plate, formed from distal ends of the
rib portions 10f in a direction orthogonal to the rib portions 10f
and formed parallel to the intermediate plate portion 10e. The wing
portions 10g, when loaded by an external force, are subjected to
larger moment than that applied to the intermediate plate portion
10e, by an amount away from the central portion, and thus, the wing
portions 10g are formed thicker than the intermediate plate portion
10e. In a specific example, the wing portions 10g are formed with a
plate thickness T3 of 3.0 mm.
[0093] The support bar 1 is formed so that the lightening hole
portions 10 satisfy the following equation:
T1<T3<T2 [0094] where T1 represents the plate thickness of
the intermediate plate portion 10e (which is equal to or more than
2 mm, or preferably is 2 to 3 mm), T2 represents the plate
thickness of the rib portion 10f (which is equal to or more than 1
mm, or preferably is 1 to 2 mm), and T3 represents the plate
thickness of the wing portion 10g (which is equal to or more than 3
mm, or preferably is 3 to 4 mm).
[0095] (Configuration of End Lightening Hole Portion)
[0096] As shown in FIG. 1 and FIGS. 3A and 3B, the end lightening
hole portions 15 are recesses formed for purposes of the weight
reduction of the suspension arm member S, as is the case with the
above-described lightening hole portions 10. The end lightening
hole portions 15 are formed extending from the vicinity of the neck
portions le at the ends of the support bar 1 to flange portions 2d
formed on outer peripheries of the connecting portions 2 via left
and right partition walls 15a. The end lightening hole portions 15
each formed in a shape of a recessed portion are formed of the left
and right partition walls 15a which form partitions in the
left-to-right direction, upper and lower wall portions 15b which
form walls in the top-to-bottom direction, and front and rear
partition walls 15c which form partitions in the front-to-rear
direction.
[0097] In the end lightening hole portions 15, the left and right
partition walls 15a and the front and rear partition walls 15c are
formed with substantially the same thickness (for example, a
thickness of the order of 2 mm) and are formed thinner than a
thickness (for example, about 3 mm) of the upper and lower wall
portions 15b.
[0098] The left and right partition walls 15a are formed of
standing walls in the form of flat plates, formed straight in the
front-to-rear direction at a predetermined distance from ends of
the front and rear partition walls 15c in the left-to-right
direction and an outer peripheral portion of the housing portion
2a.
[0099] The upper and lower wall portions 15b are horizontal walls
which form upper and lower surfaces of the neck portions le of the
support bar 1 and the flange portions 2d of the connecting portions
2, and are formed continuously from the above-described wing
portions 10g in the left-to-right direction.
[0100] The front and rear partition walls 15c are vertical walls
which partition frontward and rearward the end lightening hole
portions 15 formed in a back-to-back relation in the front-to-rear
direction, and are formed along the centerline of the support bar
1, as seen in the plan view.
[0101] (Configuration of Connecting Portion)
[0102] As shown in FIG. 1, the connecting portions 2, 2 are parts
to connect suspension members, and are formed in the end portions,
respectively, of the support bar 1. The connecting portion 2
includes the housing portion 2a substantially in a shape of a
container, integrally formed with each end portion of the support
bar 1, a recessed portion 2b formed within the housing portion 2a,
a mounting hole 2c formed in an inner bottom of the recessed
portion 2b, and the flange portion 2d formed on the outer
peripheral portion of the housing portion 2a. For example, the
right connecting portion 2 is formed in a symmetrical shape with
respect to the left connecting portion 2.
[0103] The housing portion 2a is a part to which the ball seat 3
rotatably supporting the ball portion 4a of the stud bolt 4 is
fitted, and the housing portion 2a is formed in substantially a
bottomed cylindrical shape.
[0104] The recessed portion 2b is formed of a cylindrical-shaped
recess, and is formed in a direction orthogonal to a direction in
which the support bar 1 extends.
[0105] The mounting hole 2c is a through-hole into which a
rivet-shaped heat caulking portion 3a formed on and protruding from
a lower end surface of the ball seat 3 is inserted and mounted, and
the plural mounting holes 2c are formed.
[0106] The flange portion 2d is a reinforcing part substantially in
the form of a thick plate, formed on the outer peripheral portion
of the housing portion 2a, and is formed in substantially a C-ring
shape as seen in the plan view. The flange portion 2d is formed on
the outer peripheral portion of the housing portion 2a thereby to
keep strength of the connecting portion 2. In the flange portion
2d, the end lightening hole portion 15 (see FIG. 5D) is formed open
in the front-to-rear direction.
[0107] (Configuration of Seat Ball)
[0108] The ball seat 3 is a bearing member which forms a pivot
bearing rotatably journaling the ball portion 4a of the stud bolt
4. The ball seat 3 includes the plural rivet-shaped heat caulking
portions 3a, an oil reservoir 3b for reserving lubricating oil, a
spherical surface portion 3c formed for adaptation to the shape of
the ball portion 4a, and a flange portion 3d disposed on an open
edge of the recessed portion 2b.
[0109] (Configuration of Stud Bolt)
[0110] The stud bolt 4 is a metallic bolt which functions as a stem
portion rotatably disposed in the connecting portion 2 and as a
connecting bolt. The stud bolt 4 includes the ball portion 4a
formed on a proximal end side and forming a ball joint, a boot
engagement groove 4b to which a distal end opening 5a of the dust
boot 5 is fitted, and an external thread portion 4c on which an
internal thread portion of the suspension member (not shown) is
screwed. Note that a rotation-restraining protrusion (not shown)
for preventing the connected suspension members from being loosened
is formed in a proximal end portion of the external thread portion
4c.
[0111] (Configuration of Dust Boot)
[0112] The dust boot 5 is a boot made of rubber, covering an upper
outer peripheral portion of the ball portion 4a, and is disposed in
the ball seat 3 and the stud bolt 4 in such a manner that it is
shrinkable in the top-to-bottom direction and in the left-to-right
direction. The dust boot 5 includes the distal end opening 5a
formed on the distal end side, a proximal end opening 5b formed on
the proximal end side, and a deformable cover portion 5c formed
between the distal end opening 5a and the proximal end opening 5b.
Grease for the ball joint for lubricating the ball portion 4a is
injected into the dust boot 5.
[0113] (Functions)
[0114] Next, description will be given with reference to the
accompanying drawings with regard to functions of the suspension
arm member S according to the embodiment of the present
invention.
[0115] The support bar 1 of the suspension arm member S shown in
FIG. 1 is formed by resin molding the resin material including the
fiber reinforcement material added thereto and including the
engineering plastic or the super engineering plastic containing any
of PA 66, PA 6, PPS, and POM. Thus, the support bar 1 has strength,
rigidity, and heat resistance. The support bar 1 includes the
plural lightening hole portions 10 and end lightening hole portions
15 formed in the shape of the recessed portions and is made of the
resin material, which thus enables reducing the resin material for
the support bar 1 by the amount of lightening and hence achieving a
weight reduction and a cost reduction. Moreover, the support bar 1
can improve the strength by a partition part in which the
lightening hole portions 10 are formed.
[0116] As shown in FIG. 1 and FIGS. 3A and 3B, moreover, the
lightening hole portions 10 include the front upper lightening hole
portions 11 formed in the longitudinal direction in the front upper
portion la of the support bar 1, the front lower lightening hole
portions 12 formed in the front lower portion 1b of the support bar
1 and staggered in the top-to-bottom direction with respect to the
front upper lightening hole portions 11, the rear upper lightening
hole portions 13 formed in the rear upper portion 1c of the support
bar 1 and staggered in the front-to-rear direction with respect to
the front upper lightening hole portions 11, and the rear lower
lightening hole portions 14 formed in the rear lower portion 1d of
the support bar 1 and staggered with respect to the rear upper
lightening hole portions 13 and the front lower lightening hole
portions 12.
[0117] Thus, the suspension arm member S includes the arrangement
of the lightening hole portions 10 formed in the front and the rear
of the support bar 1 and staggered in the top-to-bottom direction
and in the longitudinal direction, which in turn enables reducing
the resin material for the support bar 1 by the amount of
lightening and hence achieving the cost reduction and the weight
reduction.
[0118] Moreover, in the support bar 1, the lightening hole portions
10 and the end lightening hole portions 15 formed in large numbers
are symmetrically disposed about the centerline in the
top-to-bottom direction and in the left-to-right direction, and
thus, if the support bar 1 is loaded by an external force, the
entire support bar 1 can absorb the external force in a
well-balanced manner.
[0119] As shown in FIGS. 5B and 5C, in the support bar 1, the parts
in which the lightening hole portions 10 are formed are formed in
substantially the S-shape or in substantially the inverted S-shape,
as seen in the cross-sectional view in the widthwise direction,
which thus enables an improvement in rigidity of the lightening
hole portions 10.
[0120] As shown in FIG. 2A, the lightening hole portions 10 are
formed so that the plate thickness T1 of the intermediate plate
portion 10e, the plate thickness T2 of the rib portion 10f and the
plate thickness T3 of the wing portion 10g satisfy the following
equation: T1<T3<T2, and thus, during resin molding, resin
fluidity can be applied to requirements for higher strength. Thus,
the support bar 1 having rigidity can be achieved.
[0121] As shown in FIG. 3B, in the lightening hole portions 10, the
sidewalls 10c formed extending from the openings 10a to the inner
bottom portions 10b of the lightening hole portions 10 are formed
so as to have the angle .theta. of inclination such that the
sidewalls 10c are expanded to the openings 10a in the fan shape as
seen in the cross-sectional view. Thus, the support bar 1 enables
easy removal of a mold after the resin molding and hence
eliminating formation of burr or the like and also enables
improving workability of mold operation.
[0122] Moreover, the sidewalls 10c are formed so as to be expanded
in the opposite direction to the adjacent respective lightening
hole portions 10, which thus enables the resin molding so as to
suppress the falling down of the wing portions 10g at an open end
side by a truss effect and also enables ensuring uniform strength
in an axial direction.
[0123] As shown in FIG. 1, moreover, the stud bolts 4, 4 disposed
on the ends of the support bar 1 are screwed to the internal thread
portions of the suspension members (not shown), and thereby, the
suspension arm member S is connected to the suspension members and
disposed in a lower portion of the vehicle body. Thus, even if mud
and sand or the like enters into the lightening hole portions 10
during the travel of the automobile, the lightening hole portions
10 are formed so as to have an angle .theta. of inclination of 91
to 100 degrees such that the lightening hole portions 10 are
expanded, which in turn enables automatic elimination of the mud
and sand or the like by vibrations from the automobile.
[0124] Then, when the automobile travels, the support bar 1 is
loaded by external forces in the top-to-bottom and left-to-right
directions and in a direction of rotation with the suspension
members interposed in between.
[0125] As shown in FIG. 3B, moreover, the corner portions 10d of
the lightening hole portions 10 are rounded with their respective
predetermined radii of curvature (the curves Ra, Rb or the
spherical curved surface Rc), which thus enables suppressing a
situation where stresses concentrate at the corner portions 10d and
hence break the corner portions 10d when other members or the like
collides against the corner portions 10d during the travel of the
automobile.
[0126] It is to be understood that the present invention is not
limited to the above-described embodiment, various modifications
and changes could be made thereto within the scope of the technical
concept of the invention, and the present invention, of course,
embraces such modified and changed inventions.
[0127] In the above-described embodiment, the description has been
given, giving the stabilizer link as an example of the suspension
arm member S; however, any member will do as long as it is an
arm-shaped member for use in the suspension, and its application or
installed position or the like is not particularly limited.
[0128] Moreover, anything may be adopted as the support bar 1 as
long as it includes the front upper lightening hole portions 11,
the front lower lightening hole portions 12, the rear upper
lightening hole portions 13 and the rear lower lightening hole
portions 14, and the number, size and shape of the lightening hole
portions 10 may be appropriately changed according to the size of
the suspension arm member S, or the like.
[0129] For example, if the support bar 1 is large in size,
according to the size of the support bar 1, the number of the
lightening hole portions 10 in the left-to-right direction may be
increased, or the lightening hole portions 10 may be appropriately
increased in three, four or five stages or the like in the
top-to-bottom direction.
REFERENCE SIGNS LIST
[0130] 1: support bar [0131] 1a: front upper portion [0132] 1b:
front lower portion [0133] 1c: rear upper portion [0134] 1d: rear
lower portion [0135] 2: connecting portion [0136] 10: lightening
hole portion [0137] 10a: opening [0138] 10b: inner bottom portion
[0139] 10c: sidewall [0140] 10d: corner portion [0141] 10e:
intermediate plate portion [0142] 10f: rib portion [0143] 10g: wing
portion [0144] 11: front upper lightening hole portion [0145] 12:
front lower lightening hole portion [0146] 13: rear upper
lightening hole portion [0147] 14: rear lower lightening hole
portion [0148] Ra, Rb: curves [0149] Rc: spherical curved surface
[0150] S: suspension arm member [0151] T1: plate thickness of
intermediate plate portion [0152] T2: plate thickness of rib
portion [0153] T3: plate thickness of wing portion [0154] .theta.:
angle of inclination
* * * * *